Previously we have developed jet travel plans assuming phase advances of 1.5 h/day and phase delays of 2 h/day, given appropriately timed bright light after landing. For example, in a study in which the sleep schedule was shifted 12 h, which is the largest possible shift, circadian rhythms shifted 9.6 h over the first 4 days when they phase delayed (2.4 h/day or 144 min/day) and 6.2 h when they phase advanced (1.6 h/day or 93 min/day, see Fig. Laboratory studies with an abrupt shift of the sleep/wake schedule, which mimics what happens after jet travel, show that the circadian clock can phase shift faster when people are exposed to bright light at the appropriate time. Early estimates from real jet travelers are that the circadian clock phase delays 92 min/day after westward flights and phase advances 57 min/day after eastward flights. Thus most humans already have a natural tendency to drift slighter later each day, and it is much more difficult to phase advance the human circadian clock than to phase delay it, even in older people. It takes longer to reset or re-entrain the circadian clock following eastward than westward flight, which can be explained, at least in part, by the fact that the average free-running period (tau) of the human circadian clock is slightly longer than 24 h.
You are trying to go to sleep earlier, to advance the time of your sleep, and your internal circadian clock has to phase advance to re-align with your advanced sleep schedule and the new local time. Chicago to Paris) and expect to go to sleep at midnight in Paris, you are really trying to go to sleep at 5:00 pm according to the time of your circadian clock, which is still on Chicago time. For example, if you flew east 7 time zones (e.g. However, your circadian clock has to be reset earlier, and the technical term is a phase advance. is to say that Europe is ahead of us, and when you arrive there you have to set your wristwatch ahead by moving the hands later. For example, when it is early in the day in the U.S., it may already be approaching nighttime in Europe. Flying east requires a phase advance of the circadian clock, and flying west requires a phase delay. Thus, the symptoms of jet lag dissipate as the circadian clock is gradually reset (gradually phase shifts) to re-align (re-entrain) to the time cues (zeitgebers) of the new time zone, primarily the LD cycle. Jet lag is caused by a temporary misalignment between the endogenous circadian clock, specifically the dorsomedial region of the SCN, which controls the body’s circadian rhythms and the destination time zone and sleep/wake schedule. Thus, the effects of jet lag, both short and long term, are a public health issue that need to be addressed, and there is a need to prevent or at least minimize jet lag.ĭuration of Jet Lag and Why There Is More Jet Lag After Flying East Finally, old mice subjected to weekly 6 h phase shifts in the light-dark (LD) cycle died sooner when the LD cycle was advanced (equivalent to trips east across 6 time zones) than when it was delayed (trips west), and both groups died sooner than controls who were not shifted. Work in mice has shown that chronic jet lag accelerates the development of malignant tumors and reduces survival times. There is an increased risk of cancer in flight attendants who frequently fly across many time zones. Following transmeridian travel it is likely that meals will be eaten at inappropriate circadian phases, and repeated occurrence of this could increase the risk of cardiovascular disease and type II diabetes. Cognitive deficits, temporal lobe atrophy, as determined by MRI scans, and disturbances in the menstrual cycle can all occur with frequent jet travel. įrequent jet travel has long term health risks. Those traveling for business and conventions took an average of 4.5 trips in the year. This census does not even include military or government flights.
residents flew overseas, with about 12 million traveling to Europe and 7 million to Asia. Jet lag is not just the bane of tourists it can impair the judgment of businesspeople and politicians, compromise the performance of athletes, and poses a threat to public safety as it affects diplomats and the military. Jet travel across multiple time zones produces jet lag, which includes difficulty initiating or maintaining nighttime sleep, daytime sleepiness, decreased alertness, loss of concentration, impaired performance, fatigue, irritability, disorientation, depressed mood and gastrointestinal disturbance. Symptoms, Health and Safety Consequences of Jet Lag
0 kommentar(er)
